XML 96 R81.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Litigation (Details) $ in Millions | 2 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Feb. 15, 2019 Case | Dec. 31, 2018 USD ($) Case | Oct. 24, 2014 USD ($)
Site Contingency [Abstract] |  |  |
Consent decree paid by US government | $ |  |  | $ 2.3
Silica Cases [Member] |  |  |
Loss Contingency, Information about Litigation Matters [Abstract] |  |  |
Number of pending cases |  | 3 |
Cumulative number of cases dismissed |  | 1,493 |
Number of cases dismissed |  | 0 |
Number of lawsuits settled |  | 1 |
Asbestos Cases [Member] |  |  |
Loss Contingency, Information about Litigation Matters [Abstract] |  |  |
Number of pending cases |  | 34 |
Cumulative number of cases dismissed |  | 57 |
Number of new cases filed |  | 14 |
Number of cases dismissed |  | 4 |
Number of cases claim liability |  | 25 |
Number of allege liability |  | 6 |
Number of cases with no alleged exposure date |  | 5 |
Asbestos Cases [Member] | Subsequent Event [Member] |  |  |
Loss Contingency, Information about Litigation Matters [Abstract] |  |  |
Number of new cases filed | 4 |  |
Asbestos Cases [Member] | AMCOL International Corporation [Member] |  |  |
Loss Contingency, Information about Litigation Matters [Abstract] |  |  |
Number of allege liability |  | 3 |
Administrative Consent Order for Contamination Associated with Historic Use of PCBs [Member] |  |  |
Site Contingency [Abstract] |  |  |
Location of plant |  | Canaan, Connecticut |
Estimated accrued remediation cost | $ |  | $ 0.4 |
Administrative Consent Order for Installation of Groundwater Contamination System [Member] |  |  |
Site Contingency [Abstract] |  |  |
Location of plant |  | Adams, Massachusetts plant |
Estimated accrued remediation cost | $ |  | $ 0.4 |
Estimated cost of wastewater treatment upgrades, lower range | $ |  | 6.0 |
Estimated cost of wastewater treatment upgrades, upper range | $ |  | $ 8.0 |

X
- Definition Refers to the settlement amount received from US government against consent decree. + References No definition available. + Details
Name: | mtx_ConsentDecreeSettlement
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Low-end of the range estimate of the cost of wastewater treatment facilities upgrade at the entity's Adams, Massachusetts plant. + References No definition available. + Details
Name: | mtx_EstimatedCostOfWastewaterTreatmentUpgradesLowerRange
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition High-end of the range estimate of the cost of wastewater treatment facilities upgrade at the entity's Adams, Massachusetts plant. + References No definition available. + Details
Name: | mtx_EstimatedCostOfWastewaterTreatmentUpgradesUpperRange
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cumulative number of claims dismissed. + References No definition available. + Details
Name: | mtx_LossContingencyClaimsDismissedCumulativeNumber
Namespace Prefix: | mtx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Refers to number of allege liability during the period. + References No definition available. + Details
Name: | mtx_NumberOfAllegeLiability
Namespace Prefix: | mtx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Refers to number of cases claim liability during the period. + References No definition available. + Details
Name: | mtx_NumberOfCasesClaimLiability
Namespace Prefix: | mtx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Refers to number of cases which no period of alleged exposure by the plaintiffs. + References No definition available. + Details
Name: | mtx_NumberOfCasesWithNoAllegedExposureDate
Namespace Prefix: | mtx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
Name: | us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_EnvironmentalRemediationObligationsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of claims dismissed. + References No definition available. + Details
Name: | us-gaap_LossContingencyClaimsDismissedNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of claims settled. + References No definition available. + Details
Name: | us-gaap_LossContingencyClaimsSettledNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_LossContingencyInformationAboutLitigationMattersAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total number of new claims filed pertaining to a loss contingency during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 + Details
Name: | us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of pending claims pertaining to a loss contingency. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349 + Details
Name: | us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Name of the individual site or other grouping of the contingency. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 10 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13237-110859 + Details
Name: | us-gaap_SiteContingencyNameOfSite
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=mtx_SilicaCasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=mtx_AsbestosCasesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mtx_AmcolInternationalCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EnvironmentalRemediationSiteAxis=mtx_AdministrativeConsentOrderForContaminationAssociatedWithHistoricUseOfPcbsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_EnvironmentalRemediationSiteAxis=mtx_AdministrativeConsentOrderForInstallationOfGroundwaterContaminationSystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |